Divergences among the early thinkers of the Enlightenment show that, while they shared many of the same premises and questions, the answers they found differed widely. The spread of this spirit of inquiry and debate owed a great deal to the work of the philosophes, a group of influential intellectuals in France who proudly proclaimed that they were bringing the light of knowledge to their ignorant fellow creatures.

To appeal to the public and get around the censors, the philosophes wrote novels and plays, histories and philosophies, and dictionaries and encyclopedias, all filled with satire and double meanings to spread their message. One of the greatest philosophes, the baron de Montesquieu (mahn-tuhs-KYOO) (1689–1755) pioneered this approach in The Persian Letters, a social satire published in 1721. This work consists of letters supposedly written by two Persian travelers, Usbek and Rica, who as outsiders see European customs in unique ways and thereby allow Montesquieu a vantage point for criticizing existing practices and beliefs.

Disturbed by the growth in royal power under Louis XIV and inspired by the example of the physical sciences, Montesquieu set out to apply the critical method to the problem of government in The Spirit of Laws (1748). Arguing that forms of governments were shaped by history, geography, and customs, Montesquieu identified three main types: monarchies, republics, and despotisms. A great admirer of the English parliamentary system, Montesquieu argued for a separation of powers, with political power divided among different classes and legal estates holding unequal rights and privileges. Montesquieu was no democrat; he was apprehensive about the uneducated poor, and he did not question the sovereignty of the French monarch. But he was concerned that absolutism in France was drifting into tyranny and believed that strengthening the influence of intermediary powers was the best way to prevent it. Decades later, his theory of separation of powers had a great impact on the constitutions of the United States in 1789 and of France in 1791.

The most famous philosophe was François-Marie Arouet, known by the pen name Voltaire (1694–1778). In his long career, Voltaire wrote more than seventy witty volumes, hobnobbed with royalty, and died a millionaire because of shrewd business speculations. His early career, however, was turbulent, and he was twice arrested for insulting noblemen. To avoid a prison term, Voltaire moved to England for three years, and there he came to share Montesquieu’s enthusiasm for English liberties and institutions.

Returning to France, Voltaire met Gabrielle-Emilie Le Tonnelier de Breteuil, marquise du Châtelet (1706–1749), a gifted noblewoman. Madame du Châtelet invited Voltaire to live in her country house at Cirey in Lorraine and became his long-time companion (under the eyes of her tolerant husband). Passionate about science, she studied physics and mathematics and published the first French translation of Newton’s Principia, still in use today. Excluded from the Royal Academy of Sciences because she was a woman, Madame du Châtelet had no doubt that women’s limited role in science was due to their unequal education. Discussing what she would do if she were a ruler, she wrote, “I would reform an abuse which cuts off, so to speak, half the human race. I would make women participate in all the rights of humankind, and above all in those of the intellect.”2

While living at Cirey, Voltaire wrote works praising England and popularizing English scientific progress. Yet, like almost all the philosophes, Voltaire was a reformer, not a revolutionary. He pessimistically concluded that the best form of government was a good monarch, since human beings “are very rarely worthy to govern themselves.” Nor did Voltaire believe in social and economic equality. The only realizable equality, Voltaire thought, was that “by which the citizen only depends on the laws which protect the freedom of the feeble against the ambitions of the strong.”3

Voltaire’s philosophical and religious positions were much more radical. Voltaire believed in God, but he rejected Catholicism in favor of deism, belief in a distant, noninterventionist deity. Drawing on mechanistic philosophy, he envisioned a universe in which God acted like a great clockmaker who built an orderly system and then stepped aside and let it run. Above all, Voltaire and most of the philosophes hated religious intolerance, which they believed led to fanaticism and cruelty.

The strength of the philosophes lay in their number, dedication, and organization. Their greatest achievement was a group effort — the seventeen-volume Encyclopedia: The Rational Dictionary of the Sciences, the Arts, and the Crafts, edited by Denis Diderot (1713–1784) and Jean le Rond d’Alembert (1717–1783). The two men set out in 1751 to find coauthors who would examine the rapidly expanding whole of human knowledge and teach people to think critically about all matters.

Completed in 1765 despite opposition from the French state and the Catholic Church, the Encyclopedia contained hundreds of thousands of articles by leading scientists, writers, skilled workers, and progressive priests. Science and the industrial arts were exalted, religion and immortality questioned. Intolerance, legal injustice, and out-of-date social institutions were openly criticized. The Encyclopedia also included thousands of articles describing non-European cultures and societies, including acknowledgment of Muslim scholars’ contribution to the development of Western science. Summing up the new worldview of the Enlightenment, the Encyclopedia was widely read, especially in less expensive reprint editions.

After about 1770 a number of thinkers and writers began to attack the philosophes’ faith in reason and progress. The most famous of these was the Swiss intellectual Jean-Jacques Rousseau (1712–1778). Rousseau was both one of the most influential voices of the Enlightenment and, in his rejection of rationalism and social discourse, a harbinger of reaction against Enlightenment ideas. Like other Enlightenment thinkers, Rousseau was passionately committed to individual freedom. Unlike them, however, he attacked rationalism and civilization as destroying, rather than liberating, the individual. Warm, spontaneous feeling, Rousseau believed, had to complement and correct cold intellect. Moreover, he asserted, the basic goodness of the individual and the unspoiled child had to be protected from the cruel refinements of civilization. Rousseau’s ideals greatly influenced the early romantic movement, which rebelled against the culture of the Enlightenment in the late eighteenth century.

Rousseau also called for a rigid division of gender roles, arguing that women and men were radically different beings. According to Rousseau, because women were destined by nature to assume a passive role in sexual relations, they should also be passive in social life and devote themselves to taking care of their husbands and children. (See “Viewpoints 19.1: Jean-Jacques Rousseau and Mary Wollstonecraft on Women’s Nature and Education.”) Additionally, he believed that women’s love for displaying themselves in public, attending salons, and pulling the strings of power was unnatural and had a corrupting effect on both politics and society.

Rousseau’s contribution to political theory in The Social Contract (1762) was based on two fundamental concepts: the general will and popular sovereignty. According to Rousseau, the general will is sacred and absolute, reflecting the common interests of all people, who have displaced the monarch as the holder of sovereign power. The general will is not necessarily the will of the majority, however. At times the general will may be the authentic, long-term needs of the people as correctly interpreted by a farseeing minority. Little noticed before the French Revolution, Rousseau’s concept of the general will appealed greatly to democrats and nationalists after 1789.